This protocol is designed for the screening of patients with either diagnosed or undiagnosed conditions, and serves as a first step for individuals who may be eligible and wish to participate in NEI clinical research studies. Each individual will be thoroughly evaluated during the screening process to determine if they are suitable candidates for inclusion in any of the NEI ongoing studies. The screening evaluation will include past and current medical histories, and an appropriate physical examination. Other routine diagnostic procedures and tests may also be completed in order to help determine a subject's eligibility. These tests and procedures are of minimal risk. Once the screening process is completed and their eligibility is assessed, the subjects will be informed of their options to participate in one or more of the current research studies. If no appropriate protocol is identified, recommendations for other treatment options may be given to the individual, their primary doctor, or referring physician.